How to avoid “is not a function” error in javascript

I have a code to remove the milliseconds of a video duration, but when I try to remove it with c1seconds.setMilliseconds(0) but I get the error is not a function.

Here is my code:

var test = document.getElementById('test');
setInterval(function asas() {
if(video.readyState > 0) {
    var minutes = parseInt(video.currentTime / 60, 10);
    var seconds = video.currentTime % 60;
    var c1seconds = seconds.setMilliseconds(0);
test.innerHTML = minutes + ":" + c1seconds;
}
}, 0100);

Note: I am a beginner in javascript and I need an answer without the use of jquery